The invention relates to a composite material for medical or paramedical, particularly orthopaedic use, which comprises a thermoplastic composition based on polycaprolactone and polyurethane.
A thermoplastic composition based on polycaprolactone and polyurethane is known from EP-A-0 087 329.
The polyurethane is formed in situ in soft form in the polycaprolactone from a polyol and at least one poly-isocyanate.
The resulting polycaprolactone-polyurethane composition is manufactured in the shape of plates or sheets, and it is being used as such to replace plaster bandages.
The composition is made soft and self-adhesive by heating same above 60.degree. C., by dipping into hot water, and thereafter is put in the desired shape on the body. Parts of the material are stuck to one another. After cooling, the material forms a rigid unit.
The arrangement in position of such material is however not easy because it is highly self-adhesive in plastic condition. Once portions thereof have been brought against one another, it is substantially impossible to release these portions thereafter. It is therefore not possible to present a strip of this material in the form of a roll, unless a sheet is intercalated between the windings to prevent sticking the windings together. Correcting faults when applying the material is also impossible in practice. However, the material cools very fast, in such a way that it also becomes rigid again quite fast and the time interval during which said material can be applied in position is limited.
The composite material is also in direct contact with the body. This may not only cause allergic reactions due to chemicals possibly still present in the material, but it is mostly uncomfortable due to the relatively high temperature at the beginning of the application. Due to direct contact of the material with the skin, breathing through the skin is hampered.
There is known from U.S. Pat. No. 3,728,206, a material based on polyurethane and polycaprolactone, but such material is formed by impregnating a single layer of non-thermoplastic polyurethane foam with a caprolactone for example.
Said material which is also used for replacing plaster bandages is softened by heating above 49.degree. C., preferably above 82.degree. C.
It is however so strongly adhesive that it is generally protected with a coating, for example an aluminum foil. When said material is handled in rolls, it is coated on one side with silicone-processed paper to prevent the windings sticking to one another.
The requirement of having to remove such protection when using the material makes the application thereof difficult. The material is not self-supporting. A spool has to be used to support the roll windings.
Moreover with this material also, no correction is possible any more once portions of the material in plastic condition have contacted one another. Releasing such portions is substantially impossible due to inadvertently sticking together of the strips of the material and the impossibility to release the parts stuck together, winding the material around moving body parts, is nearly impossible. The person applying the material has to wear gloves.
Direct contact of the material with the skin should further be avoided, on the one hand possibly because of the relatively high temperature which is required to make the material plastic and workable, and on the other hand to prevent the action of possible chemicals on the skin. This is the reason why according to the American patent, the material is not laid directly on the body, but an orthopaedic stocking is first put on. Thereby the drawbacks of the direct contact are indeed avoided and the skin can breathe, but the orthopaedic stocking is relatively costly and the requirement of such a stocking makes the application of the orthopaedic bandage time-consuming and more difficult.
The invention has for object to obviate said drawbacks and to provide a composite material for medical or paramedical, particularly orthopaedic use, the use of which is very simple and unexpensive and notably plastic portions of which brought against one another, may be released again, which composite material can be applied directly on the skin without danger or uncomfortable feeling and lets the skin breathe, in such a way that the use of orthopaedic stockings or similar protections between the skin and the material is superfluous.